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In-situ measurement via the flow-through method and numerical simulations for radon exhalation during measurements of the radon exhalation rate

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Nuclear Science and Techniques 2024年第7期35卷 28-43页

作者： Ming Xia Yong-jun Ye Shan-Wei Shang Ting Yu Dai-jia chen School of Resources Environment and Safety Engineering University of South China Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy University of South China

Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two methods. An abnormal radon exhalation behavior was observed, leading to computational fluid dynamics（CFD）-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was considered. Based on the in-situ experimental and numerical simulation results, variations in the radon exhalation rate subject to permeability, flow rate, and insertion depth were quantified and analyzed. The in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method, which could be explained by the negative pressure difference between the inside and outside of the chamber during the measurements. The consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air interface. The synergistic effects of the three factors（insertion depth, flow rate, and permeability） on the negative pressure difference and measured exhalation rate were quantified, and multivariate regression models were established, with positive correlations in most cases; the exhalation rate decreased with increasing insertion depth at a permeability of 1 × 10-11m2. CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.

关键词： Radon exhalation Flow-through Numerical simulation Accumulation chamber Multivariate regression

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预测典型变形高温合金均匀化动力学的新模型

Transactions of Nonferrous Metals Society of China 2024年第4期34卷 1178-1190页

作者：张献光杨文超周扬闫建昊肖东平税烺付建辉孙飞石鹏陈佳俊裴逸武张健北京科技大学绿色低碳钢铁冶金全国重点实验室北京100083 北京科技大学冶金与生态工程学院北京100083 成都先进金属材料产业技术研究院股份有限公司成都610300 攀钢集团研究院有限公司攀枝花617000 Department of Material Design Innovation Engineering Nagoya UniversityFuro-choChikusa-kuNagoya 464-8603Japan

提出一种基于扩散距离概念的变形高温合金均匀化动力学新预测模型。通过定量电子探针(EPMA)分析,系统研究典型镍基变形高温合金(GH4141)的微观偏析和均匀化动力学。研究发现,基于残余偏析指数模型预测的均匀化动力学与实际测量结果之间... 详细信息

提出一种基于扩散距离概念的变形高温合金均匀化动力学新预测模型。通过定量电子探针(EPMA)分析,系统研究典型镍基变形高温合金(GH4141)的微观偏析和均匀化动力学。研究发现,基于残余偏析指数模型预测的均匀化动力学与实际测量结果之间存在一定差异。实验和理论分析均表明,考虑了过去通常被忽略的扩散方向因子的一维扩散距离模型可以合理地预测均化动力学。新模型在只需知道原始枝晶臂间距和扩散系数前提下即可完成预测计算,这为变形高温合金均匀化动力学预测提供了一种新的选择。

关键词：变形高温合金微观偏析均匀化动力学预测模型扩散距离

New method for multibody dynamics based on unknown constraint force

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Science China(Technological Sciences) 2024年第3期67卷 791-808页

作者： TIAN Ying jia YingHong ZHANG jun School of Astronautics Beihang UniversityBeijing 100191China Beijing Institute of Control Engineering Beijing 100190China National Laboratory of Space Intelligent Control Beijing 100190China

This paper presents a new method for the dynamics of multibody systems based on unknown constraint force. The method can uniformly solve multibody systems with typical configurations, including the system with rigid-flexible coupling, the system in tree topology, and the system with loop constraints. Unlike common methods, the proposed method can model the loop system without “cutting off” loop constraints, leading to the exact same modelling process as the tree-like system performs. Based on graph theory, a topological record matrix M_(rec) is proposed to capture the arbitrary system configuration. Moreover, constraint forces are selected as the key variables in semi-recursive framework. With the recursive kinematics relationship between adjacent bodies, the constraint force equation is further assembled to achieve the full-state system solution. The numerical simulations demonstrate the accuracy of the proposed method.

关键词： multibody system dynamic modelling rigid-flexible coupling unknown constraint force graph theory semi-recursive algorithm

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Nitrite-catalyzed economic and sustainable bromocyclization of tryptamines/tryptophols to access hexahydropyrrolo[2,3-b]indoles/tetrahydrofuroindolines in batch and flow

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Chinese Chemical Letters 2024年第07期35卷 273-278页

作者： Xiao Xiao Biao chen jia-Wei Li jun-Bo Zheng Xu Wang Hang Zhao Fen-Er chen Institute of Pharmaceutical Science and Technology Collaborative Innovation Center of Yangtze River Delta Region Green PharmaceuticalsZhejiang University of Technology College of Chemistry and Chemical Engineering Jiangxi Normal University Engineering Center of Catalysis and Synthesis for Chiral Molecules Department of ChemistryFudan University Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Drugs

A highly efficient and concise bromocyclization has been successfully achieved, in which tryptamine/tryptophol derivates can be transformed to valuable HPI/TFI scaffolds with economic and green manners. Moreover, a controllable cascade transformation of bromocyclization and aromatic bromination has also been smoothly achieved to form dibrominated HPIs and TFIs. Production could be successfully scaled up under both the batch process and a continuous flow fashion. The most remarkable peculiarity of our process over all previous methods is that the generated water is the major ***, successful application of this new protocol has been demonstrated by the pharmaceutical and natural products syntheses.

关键词： Bath and flow Economic and sustainable bromocyclization HPI and TFI structures Nitrite Tryptamines and tryptophols

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An origami shield with supporting frame structures optimized by a feature-driven topology optimization method

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Defence Technology（防务技术） 2024年第1期31卷 447-456页

作者： Dongsheng jia Pengcheng Feng Liangdi Wang Longcan chen jun Wang Jihong Zhu Yingjie Xu Weihong Zhang State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi'an710072China

In this paper,the design,manufacture and testing of an origami protective shield with a supporting frame structure are *** consists of an origami shield surface and a deployable supporting frame structure that needs to be portable and sufficiently ***,for the design of the shield surface,a threestage origami crease pattern is developed to reduce the shield size in the folded *** shield surface consists of several stiff modular panels and layered with flexible *** modular panels are made of a multi-layer composite where a ceramic layer is made of small pieces to improve durability as those small pieces enable restriction of crack ***,the supporting frame structure is designed as a chain-of-bars structure in order to fold into a highly compact state as a bundle of bars and deploy in ***,a feature-driven topology structural optimization method preserving component sequence is developed where the inter-dependence of sub-structures is taken into account.A bar with semi-circular ends is used as a basic design *** positions of the bar’s end points are treated as design variables and the width of the bars is kept ***,a constraint on the total length of the chain of bars is ***,the modular panels made of multi-layer composite and the full-scale prototype of the origami shield are fabricated and tested to verify the bullet-proof performance.

关键词： Origami Deployable structure Structure design Shield Composite materials

Pre-Train and Learn: Preserving Global Information for Graph Neural Networks

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Journal of Computer Science & Technology 2021年第6期36卷 1420-1430页

作者： Dan-Hao Zhu Xin-Yu Dai jia-jun chen Library Jiangsu Police InstituteNanjing 210031China Department of Computer Science and Technology Nanjing UniversityNanjing 210093China

Graph neural networks(GNNs)have shown great power in learning on ***,it is still a challenge for GNNs to model information faraway from the source *** ability to preserve global information can enhance graph representation and hence improve classification *** the paper,we propose a new learning framework named G-GNN(Global information for GNN)to address the ***,the global structure and global attribute features of each node are obtained via unsupervised pre-training,and those global features preserve the global information associated with the ***,using the pre-trained global features and the raw attributes of the graph,a set of parallel kernel GNNs is used to learn different aspects from these heterogeneous *** general GNN can be used as a kernal and easily obtain the ability of preserving global information,without having to alter their own *** experiments have shown that state-of-the-art models,e.g.,GCN,GAT,Graphsage and APPNP,can achieve improvement with G-GNN on three standard evaluation ***,we establish new benchmark precision records on Cora(84.31%)and Pubmed(80.95%)when learning on attributed graphs.

关键词： graph neural network network embedding representation learning global information pre-train

Synthesis of Conjugated Polymers Containing Diketopyrrolopyrrole(DPP)Building Block and the Photophysical Study

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Chinese Journal of Polymer Science 2019年第11期37卷 1092-1098页

作者： Ying-Zhong Wu Yi-chen Zhang jia-jun chen Li-Juan Fan Department of Polymer Science and Engineering College of Chemistry Chemical Engineering and Materials Science Soochow University

Sonogashira coupling of two different diketopyrrolopyrrole (DPP)-containing dihaloarenes with the same aromatic bisalkyne resulted in two new conjugated polymers with the same backbone but different pendant groups on the DPP moiety. The polymers were found to have designed chemical structures via structural characterizations in comparison with three monomers. The molecular weight measurement further demonstrated the formation of polymers with polydispersity index around 2, consistent with the polycondensation nature of the polymerization based on Sonogashira coupling. Both polymers could dissolve in many organic solvents, and the one with long alkyl side group on DPP moiety had better solubility. Photophysical investigation showed that both polymers had typical absorption/emission of conjugated polymers, and varying the solvent did not have large influence. Compared with other polar solvents, toluene reduced the quantum yield of fluorescence of the polymers, especially for the one with long alkyl pedant group, accompanying with slight red-shift in absorption/emission. The difference in the absorption/emission wavelengths between the polymers was similar to that between the corresponding monomers. Adding water into the THF solution of polymers reduced the emission intensity but no redshift was observed. Discussion about the structure-property relationships was carried out in detail.

关键词： Conjugated polymer Diketopyrrolopyrrole Building block Sonogashira coupling Photophysics

A compact X-band backward traveling-wave accelerating structure

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Nuclear Science and Techniques 2024年第5期35卷 13-29页

作者： Xian-Cai Lin Hao Zha jia-Ru Shi Qiang Gao Fang-jun Hu Qing-Zhu Li Huai-Bi chen Department of Engineering Physics Tsinghua UniversityBeijing 100084China Key Laboratory of Particle and Radiation Imaging(Tsinghua University) Ministry of EducationBeijing 100084China

Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated *** proposed a compact VHEE facility based on an X-band high-gradient high-power *** this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW ***-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test *** structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.

关键词： Backward traveling-wave accelerating structure Equivalent circuit model High-power test Very high-energy electron radiotherapy

Rogue wave solutions and rogue-breather solutions to the focusing nonlinear Schr?dinger equation

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Communications in Theoretical Physics 2024年第3期76卷 33-41页

作者： Si-jia chen Xing Lü College of Science Tianjin University of TechnologyTianjin 300384People's Republic of China Department of Mathematics Beijing Jiaotong UniversityBeijing 100044People's Republic of China Beijing Laboratory of National Economic Security Early-warning Engineering Beijing Jiaotong UniversityBeijing 100044People's Republic of China

Based on the long wave limit method,the general form of the second-order and third-order rogue wave solutions to the focusing nonlinear Schr?dinger equation are given by introducing some arbitrary *** interaction solutions between the first-order rogue wave and one-breather wave are constructed by taking a long wave limit on the two-breather *** applying the same method to the three-breather solutions,two types of interaction solutions are obtained,namely the first-order rogue wave and two breather waves,the second-order rogue wave and one-breather wave,*** influence of the parameters related to the phase on the interaction phenomena is graphically *** occur among the rogue waves and breather *** the collisions,the shape of them remains *** abundant interaction phenomena in this paper will contribute to a better understanding of the propagation and control of nonlinear waves.

关键词： nonlinear Schrodinger equation rogue wave solutions interaction solutions